1. Field of the Invention
The present invention relates generally to computer and communications networks, and more specifically to securing wireless body sensor networks using environmental data for nonce values in a key establishment protocol.
2. Description of the Related Art
Sensor networks comprise a category of computer networks, characterized by the development of small, low cost sensor devices with combined sensing and communication (often wireless) capabilities. Most applications of sensor networks rely on combining information from multiple sensor devices to establish or infer some composite state or event of the sensed environment (often called the “sensing field”). The sensor devices are typically spread across a geographic area and contain some level of intelligence for signal processing and networking of the data. A sensor device may detect and monitor the value of some parameter at a given location, such as, for example, temperature, atmospheric pressure, relative humidity, etc.
One type of sensor network is a body sensor network. Body sensor networks typically comprise sensor devices, or sensor nodes, that are worn on or implanted within the body for measuring physiological data (vital signs, motion), combined with wireless components that wirelessly transmit the measured data to an external receiver, thus allowing continuous monitoring of patients in an unobtrusive manner in any environment. Each sensor node in a network may measure one or more types of a user's physiological data.
Devices within a body sensor network must be able to communicate with one another in a secure manner to ensure a user's privacy. To facilitate secure communication, data transfers between devices in the network are encrypted using either software or hardware techniques, such as key establishment protocols. However, wearable sensor nodes introduce a new set of technical problems due to resource limitations of the sensors. In a wireless body sensor network, sensors typically comprise small memories, weak processors, limited energy, and small packet size. In addition, sensors placed on or implanted within the body have no user interface, and may exist for long periods of time. The limitations of the sensors require that sensor networks be designed with extreme power conservation. As sensor nodes have little computational power, cryptographic ciphers must be used with care.